When a person has his or her eyes examined, e.g. by an ophthalmologist using an ophthalmoscope or a slit lamp microscope, the eye to be examined should preferably be kept still in a desired orientation. When examining a small child, the child often finds it difficult to concentrate and focus the eye in one direction for long enough time. This problem is typically addressed by letting the child watch a film, a flashing light or an interesting toy. However, if the child squints in an inwards direction, the ophthalmologist or an instrument used for examination of the other eye blocks the line of sight of the focusing eye, i.e. the eye not being examined but being used to watch e.g. the film. Instead it must be tried to obtain the same effect by other means, such as by trying to convince the child to be quiet which may not be easy. This makes the examination less efficient and sometimes impossible. In the latter case it may become necessary to perform the examination while the child is under general anaesthesia. This both makes the examination more complicated and may also result in undesired side effects. The same problems as mentioned for small children may also be the case for a mentally disabled person of any age.